Apparatus for preventing the oxidation of metals



Nov. 16, 1937 w. H. D. HORSFALL ET AL APPARATUS FOR PREVENTING THEOXIDATION OF, METALS s Sheets-Sheet 1 Filed March 2, 1936 Nov. 16, 1937.w. H. D. HORSFALL ET AL 2,099,208 I .APPARATUS FOR PREVENTING THEOXIDATION OF METALS Filed March 2, 1936 3 Sheets-Sheet 2 UTI U 6111b TST. wH.D.Horsfa11 Nov; 16, 1937. I w. H. D. HdRSFALL ETAL APPARATUS FORPREVENTING THE OXIDATION OF METALS Filed March 2, 1936 3 Sheets-Sheet 3$0 m ,TZ X w\ A HB wM/W IE I4.

Patented Nov. 16, 1937 un ts!) STATE APPARAT S FOR PREVENTING THE OXIDA-'I'ION OF IVIETALS William H. D. Horsfall and Maunsell B. Jackson,

Toronto, Ontario, Canada I Application March 2, 1936, Serial No. 66,615

4 Claims. (01. 22-57) This invention relates to means for preventing theformation of oxides on the surface of castcooling periods in the processof making castings,

it has been the practice to allow themetal em- I ployed to be exposed tothe atmosphere or other sources of oxidation. This resulted in theformation of oxides, commercially called scale, on the surface of thecasting and the removal of this scale involved both cost of machiningand loss of material.

In the casting of copper wire bars this lesson account of the scale wasvery considerable and it is to the making of these wire bars withoutscale that this invention more particularly relates. The'scaie onthe=said bars is formed by the oxygen in the air combining'with thehighly heated copper to form a thin coating of CuO.

The copper immediately below this oxidized coating combines with the CuOforming CuzO which results in the finished casting having a contaminatedupper layer.

-The object of the present invention is to provide simple means forproducing cast metal which will be in proper condition for use whenremoved from its mold, and for preventing the formation of oxides on thesurface of molten metal.

We attain our object by providing means for expelling andexcluding airfrom the vicinity'of the hot. metal until such time as its temperaturedrops below the oxidation point.

Theconstructions are hereinafter more fully described and areillustrated in the accompanying drawings iii which Fig. 1 is aplan viewof part of a casting machine showing our invention applied thereto;

, Fig. 23. section on the line 2-2 in Fig. 1;

Fig. 3 a section on the line 3-3 in Fig. 1; Fig, 4 a section on the line44 in Fig. 1 showing the feed spout; pouring ladle and spouts;

Fig. 5 a section on the line .5-5 in Fig. 1;

Fig. 6 aside elevation of a modified form of machine, the hood andcasing being shown in section;

Fig. 8 a plan view of another modified form of machine;

Fig. 9 a cross-sectional detail on the line 9- -9 in Fig. 8; i

'sides of the molds are concentric;

Fig. 11 a. cross-section on the line ll'll in ig.10:' Fig. 12 across-sectional detail of a mold and Fig. '7 a cross-section on the lineIr-1 in Fig. 6; i

Fig. 10 a plan view of part of. a modified form of the invention inwhich the inner and outer hood showing a rubbing strip carried by thelatter; V

Fig. 13 a plan view of a modified form of mold in which the rubbingstrip is-parried by curved fins or projections cast integral with themold;

Fig. 14 a cross-section of the mold shown in Fig.13;

Fig. 15 a plan view of a modified arrangement of molds showing a hoodand cover thereon; and Fig. 16 a cross-section on the line l6l6 in Fig.15.

In the drawings like numerals of reference indicatecorresponding partsin the different figures.

Referring to Figs. 1 to 5, l is a Walker castingmachine which is wellknown in'the copper casting art and comprises a pluralityof molds 2'tiltably supported on radial arms 3 carried by :a turntable 4.

I The latter is'suitably supported and rotated to move the molds pastthe filling point A'to a point (not shown) where the molds are turnedupside down to dump the solidified metal therefrom. Thesurfaces of themolds which contact with the molten metal are thereafter'covered withbone ash and the molds are then turned right side up for receiving fresh-molten metal when they come round to the filling station A. I

Toexclude air from the castings in the molds until the temperature ofthe castings drops below the oxidation point, we provide a hood 5-extending transversely across but spaced from the tops of the molds. Thehood has side flanges 6' which extend downwardly past the inner andouter sides of the molds so that the latter are free to travel throughthe hood which extends longitudinally from the filling point A to apoint in the circumference of the machine where the castings have cooledto. a temperature below the oxidation point and are therefore immune tothe chemical action of oxygen. Any suitable means v such as one ormore-pipes 1 may be utilized to introduce a non-oxidizing gas, such as areducing gas, an inert gas or steam, beneath the hood 5 whereby all airtherein will be driven out and excluded therefrom.

' by providing strips I asbestos carried by -The quantity of gas used.may be minimized 8 of suitable-material such as either the molds 2 orthe hood side flanges 6 for rubbing against the other of the said parts.In Figs; 1, 3 and 5, the molds are rectangular in plan and their sidesare provided with longitudinal grooves 9 adapted to receive tangs Ill onside extensions ll having their faces adjacent the flanges 6 curved. Thesaid faces are substantially concentric to the hood flanges 6 and carrythe strips 8 for closing or substantially closing the space between theflanges 6 and extensions H. The opposite ends of each tang may betapered to receive wedges l2 between said ends and the adjacent sides atthe groove 9 whereby the extensions II are detach by. a correspondingnumber of spouts l5 on a. tiltable pouring ladle l6. The latter isfllled by a feed spout H which conveys the molten metal from a furnacel8.

Preferably the space above the molten metal" in the furnace I8 is filledwith non-oxidizing gas and the feed spout I1 is enclosed by a casing l9into'which the gas is also introduced. The casing I9 is also adapted toenclose the tiltable'pouring ladle I6 and its spouts IS. The casingcommunicates with the hood 5 so that air is excluded from the metal fromthe time it melts in the furnace until it cools in the molds to atemperature-below that of the oxidation point.

circular path, they may be pivotally carried on an endless chain 20whichpasses around sprockets, 2|, as shown in Fig. 6. The distance betweenthe sprockets 2| and the speed of the chain are such that the moltenmetal poured into the-molds at one end A? of the machine will besolidified by the time it reaches the other end of the machine. Thecastings are discharged from the molds when the latter are turned upsidedown as they are carried around the sprocket 2| at the end-of themachine remote from the filling end. During the return movement of themolds alon the underside of the machine,the cavities of the molds willbe covered with bone ash or other suitable material blown thereintothrough one or more nozzles 22. Any suitable means such as the rails 20may be provided to support the chain 20 intermediate the sprockets 2|and rails 20 are provided to support the molds while they are beingreturned in an upside down position. In this case the hood 5, which issimilar to the hood 5 except for shape, extends from the filling point A.to a pointwhere the temperature of the castings has dropped below thatat which oxidation would occur. In this case, the furnace Il may belocated in alinement with the molds and'the casing l9 encloses ,the'feedspout I19, ladle I 8. and its, The ladles l6; I6 may be tilted, by anysuitable means, to move the spouts l5, II into and out of their pouringpositions. The casing I 9 comunicates with the hood 5' and nonoxidizinggas may be introduced thereintov by one or more pipes I. The strips 8,corresponding to the hereinbefore strips 8, may be carried by the moldsor the hood side flanges B for contacting with the other of said flangeand mold parts as the molds travel between the flanges.

In Figs. 8 and 9 is shown a modified form of copper molding machine inwhich the mold' is formed as a rotatable table 23 having a cavity 23 initsupper surface. The molten metal is poured into the cavity by a spoutli while the mold is rotated slowly and by the time the mold makesnearly one revolution the metal has cooled sufficientlyto permit itsremoval from the cavity. This molding machine is known in the art andthe cast metal is removed in a continuous bar or strip which issubsequently cut into lengths for conveniently handling the cast copper.To prevent the copper from being oxidized, we apply a hood 5 over themold 23, casing l9 over the spout l5 its ladle 16 and feed spout N andintroduce a non-oxidizing gas beneath the hood 5 and easing m by anysuitable means such as one or more pipes 1 3.

the casting at its point of removal from the cavity is below theoxidation point so that the casting will not be oxidized when it passesinto the atmos phere. The flanges 6 of the hood 5 or the vertical sidesof the'mold 23 may beprovided with a rubbing strip 8 for engaging the".other of said a mold and flange parts.

' A modified form of the machine shown in Fig. 1 is disclosed in Figs.10 and 11 in which the molds 24 are segmental in shape with their innerand outer sides concentric to the hood flanges 6. The molds in this caseare provided with lugs 25 which are hinged on pins 26 carried by bosses21 on the arms 3 instead of by trunnions journalled in bearings carriedby the arms 3 in Fig. 1. The extensions II? are curved throughout theirlength to lie against the sides of the molds 24 and to be concentr'c tothe flanges 6 whereby the strips 8 will contact between the flanges. Anymeans such as a rail 28 or other suitable means may be provided tosupport the lower outer edges of the molds as they travel 'from aposition ahead of the filling station to the point where they are turnedupside down. When the end of the rail is reached, the molds will drop bygravity to the position indicated in dotted lines in Fig. 11 and'anysuitable means such as a bent rail (not shown) may be employed toenclose the recesses .in the channels to embrace the stems of theT-shaped strips which project beyond'the plates for contact with thecurved sides of molds which may be segmental as shown in Flgs, 10 and 11or rectangular with curved rubbing extensions carried thereby. As thecurved hoods 5 do not form complete circles, it is obvious that not onlymay the flanges 6, or 6 be readily drawn into shape to fit the curvededges of the tops of the hoods 5 and be secured thereto by any suitablemeans such as by welding, but the plates 32 may also be readily bent tofollow the curvature of the channels 3L,

In Figs. 13 and 14 is shown a rectangular mold the latter as the moldspass.

The rotary speed of the mold 23 is so regulated that the temperature ofhaving curved integral side extensions II which may serve for engagementby strips 8 carried by the flanges 6 or for carrying the strips 8 sothat they will engage the flanges 6.

the top of the hood 5 and is provided with deaooaaoel pendingflanges illwhich are spaced from-the -so thatthega s or vapor may ilow lengthwise01'.

-"side flanges I. The spaces between the flanges u and 6 at oppositesides of the cover communicate at their lower ends with the spacesbetween the flanges 6 and the sides of the molds. The

cover 33 is provided'with a suction outlet 35 whereby any gasesintroduced through the pipe I and escaping from the interior of the hoodwill be withdrawn through the outlet instead of escaping into the roomin which the machine is set up g g V It .will be distinctly understoodthat the term non-oxidizing gas or gaseous means used throughout thespecification and, claims is vintended to include any gas which will notliberate oxygen, any reducing gas with which oxygen will combine or anyinert gas including superheated or dry steam. I

- What weclaim'as our invention is: 1. In apparatus at the classdescribed the com-- bination of a tunnel-shaped hood formed with a topand opposed sides depending from the top;

the hood being openat the bottom throughout its length and at each endand formed as a continuous passage-way; a mold having its top,

above the level 01 the lower edges of the sides of the hood; means formoving the, mold lon itudinally into, through and out of the hood: andmeans for introducing at non-oxidizing gas 'or vapor into the hood abovethe level of the top of the moldso that the gas or vapor may flowlengthwise of the hood to the open ends to drive air iromthe hood andexclude it therefrom.

2. In apparatus 01. the class described the combination of atunnel-shaped hood formed with a top and opposed sides depending fromthe top.

the hood being open at the 'bottom throughout its length and at each endand formed as a con-' tinuous passage-way: a mold having its top abovethe level oi the-lower edges of the sides ofthe hood; means for movingthe mold longitudinally into, through and out of the hood: means forintroducing a non-oxidizing gas or vapor into the hood above ,the levelof the top 01' the mold the hood to the open ends to drive air from thehood and exclude it therefrom; mold pouring means at one end 01 thehood; and a closed casing connected-with the hood and enclosing said 5mold-pouring means .but leaving sumcient opene ing for the entrance 0!the mold.

3. In W 01 the class described the combination oi t tunnel fehaped, hoodformed with a sides of thehood having its top above the level of thelower edges of the sides of the hood; means for moving the moldlomtudinally into, through and out of the hood; means for intrdducing anon-omdimug gas or. vapor into the hood above the level of the top ofthe mold so that the gas or vapormav flow lengthwise oi the hood to theopen 'ends to drive air from the hood and exclude it therefrom; andrubbing strips arranged lengthwise oi the molds and hood substantiallyclosing the space at side between the mold and the hood and connected tothe sides of one of said mold and hood parts. 4. In apparatus of theclass described the combination oia tunnel-shaped hood formed with a topand opposed sides depending from the top, the hood being open at thebottom throughout its length and at each end and formed as a conwnmm n.D. nonsrann nauusunr. B. JACKSON.

